1. Field of the Invention
This invention relates to a pneumatic pipeline transport system for moving solid, containerized cargo. More particularly, this invention relates to a system wherein the containers themselves act as pumps to energize the system in response to an intermittently applied force on the container which sets up a moving column of air which further propels the containers.
2. Prior Art
Pipeline transport systems have been used successfully for many years for conveying fluids, such as water or petroleum, from the source of origin to areas of utilization. Pipeline transport systems have also found widespread use in conveying particulate matter or slurries, such as grain or pulverized coal. Liquids and slurries are generally propelled by a series of high-power pumps.
More recently, there have been a number of proposed pipeline transport systems for carrying solid, containerized cargo or passenger vehicles through tubular conduits. Typically, the containers or vehicles in these systems have been pneumatically or hydraulically propelled. Pneumatic propulsion of large vehicles requires complex and expensive means for generating high pressure air flow in the conduit. Maintaining the high pressure flow creates particular problems for loading and unloading vehicles into the ambient atmosphere. Hydraulic systems which have been proposed also require closed containers and powerful pumps. Moreover, such hydraulic systems present maintenance and water disposal problems.
One approach has been to propel the vehicles by the fluid momentum of low pressure air circulated at a mean velocity by external pumps. U.S. Pat. No. 3,797,405 which issued to Carstens et al on Mar. 19, 1974, describes a system wherein the driving momentum for the vehicles is generated by the rapid flow of air in the conduit. The vehicles are configured to have a high drag coefficient so that they may be accelerated to a velocity approximating the mean velocity of the driving air. Booster pumps are employed to maintain a large mass flow rate of air at a low static pressure to avoid pressure differentials in the system. Such booster pumps, however, are costly to fabricate and maintain, and are inefficient in terms of energy utilization. Moreover, such air circulating systems require special techniques for loading and unloading vehicles in the ambient atmosphere.
Other systems which are known in the art use various means of continuous propulsion for moving the vehicle along the interior of the pipeline. For example, in some known systems the vehicles are self-propelled by internal motors, or electromagnetically propelled by linear solenoid motors wherein electrical current flowing through propulsion coils produces a magnetic flow field that propels a ferro-magnetic vehicle. Such continuously propelled systems are described in U.S. Pat. No. 3,861,319, which issued to Gelhard et al on Aug. 14, 1972, and in U.S. Pat. No. 3,996,858, which issued to D. W. Sange on Dec. 14, 1977. Such systems are costly and unreliable. The inclusion of a motor in each vehicle increases both its initial cost, and the probability of mechanical breakdown. And, electromagnetically propelled systems are impractical.
It is an object of this invention to provide a transportation system which simply and economically transports said cargo between predetermined locations.
It is a further object of this invention to provide a transportation system which is simple in construction and relatively maintenance free.
It is yet a further object of this invention to provide a transportation system which is highly energy efficient; eliminating the energy inefficiencies of the prior art air pumps required to create high mass flow of an air column or the energy losses which result from continuously propelling vehicles through the system.
It is a still further object to precisely control the energy input to the system for reasons, among others, including the prevention of resonant oscillations in the system.